Section insulator for trolley systems



Nov. l5, 1938. l.. c. SPENCER SUCTION INSULATOR FOR TROLLEY SYSTEMS Filed June 26, 1936 Patented Nov. 15, 1938 UNITED STATES PATENT OFFICE SECTION INSULAT'OR FOR TROLLEY SYSTEMS Lon G. Spencer, Indianapolis, Ind.

Application June 26, 1936, Serial No. 87,359

9 Claims. (Cl. lill- 39) My invention relates, generally, to overhead the necessary strength, the construction of a trolley systems, and it has reference in particular section insulator becomes decidedly bulky when to section insulators for overhead trolley syshickory is used. tems. Resinous compounds have been used as insu- Generally, it is desirable to sectionalize the lating material in section insulators, but while power supply for overhead trolley systems. That they have good electrical qualities, they do not is, instead of having one continuousI overhead have the mechanical strength to withstand the trolley line with power supplied from a number high stresses imposed upon them. In some cases, of sub-stations, the trolley line is sectionalized, rubber compounds have been used but while they 110 each section being insulated from the other and have both the desirable mechanical and electrical 10 fed through a separate feeder. In this way, properties, their cost is excessive, as also is their should a fault such as a grounded trolley wire weight.

occur in one section, the other sections will not It may, therefore, be seen that with the conbe affected. Continuity of service is thus imtinued rapid growth of trolley-bus systems, and

` proved, and also amore balanced loading of subwith the increasing scarcity of hickory as an 15 stations is secured, as the length of line which insulating material, there is a decided need for any one sub-station may feed is limited. some new material or combination of materials In trolley bus power systems, both the positive to give an insulator the desired electrical and and negative conductor must be carried overmechanical qualities.

head as there is no ground return, the bus being The object, therefore, of my invention is to 20 insulated from the ground by rubber tires. This provide a high strength, single beam section ingreatly complicates the construction of the oversulator which will have high resistance to the head trolley at intersections, as it is necessary to deleterious effects of exposure to moisture. provide insulating means between the conductors Another object of my invention is to provide v of opposite polarity where they intersect. This a super-rigid single beam section insulator that 25 is usually accomplished through the use of secshall not swell, buckle or warp under the most tion type insulators together with the necessary adverse weather conditions.

interlocking end fittings, and the usual metallic A further object of my invention is to provide frogs or crossings. a super-rigid section insulator having renewable 3o lAs such an insulator is inserted directly into wearing parte 30 the line, it must withstand the full tension of Another object of my invention is to provide the conductor, which may amount to from 2000 a section insulator having an insulating member to 4500 lbs. This necessitates that the insulators with a metallic core of magnetic material, which not only have good dielectric qualities but also fune'iOIlS' t0 greatly reduce or prevent the burnk have a high tensile strength. In addition, as ing 0f the insulating member by the arc. 35 the insulator is directly exposed to the effects Still another object of my invention is to proof the weather, a further requirement is that it vide a weather proof super-rigid beam section be unaifected by moisture, heat, cold, etc. insulator that shall be protected from the de- These factors make the selection of a material structive effects of arcing.

40 for the body of a section insulator a difiicult A still further object of my invention is to 4o matter. Fiber, which has been used to a great provide a single beam section insulator having extent, is a good insulator and has a high tensile a core of interlocking metal strain plates molded strength, but in applications where continually in an insulating material and renewable insusubjected to moisture, such as in locations along lating wearing parts designed to protect the `4.5 the seacoast, it has shown a decided tendency main body from destructive eiects of arcing. to swell. In some installations the swelling has Other objects will in part be obvious and in been so serious as to hinder the passage of the part appear hereinafter. current collector. Further exposure to moisture My invention, accordingly, is disclosed in em- .50 body member, and in many cases, complete faildrawing, and comprises the features of construci' has resulted in a warping and buckling of the bodiments hereof shown in the accompanying ure through softening of the fibers. tion, combination of elements, arrangement of Hickory, which is one of the best insulators, parts which will be exemplified in the construcis rapidly becoming scarce, and even the best tion hereinafter set forth, and in the scope of hickory when impregnated is in time decidedly the application of which will be indicated in the vt5 affected by weathering. Also, in order to secure appended claims. 5 5

For a more complete understanding of my invention reference may be had to the following detailed description, taken in connection with the accompanying drawing, in which:

Figure l is a partially-sectionalized plan view of a trolley section insulator embodying the principal features of my invention, showing one preferred method of construction.

Fig. 2 is a side elevational View of the section insulator of Fig. 1.

Fig. 3 is a sectional view taken along the line III-III of Fig. 2, and

Fig. 4 is an end elevational view of Fig. 2.

Referring more particularly to Figs, 1 and 2, the reference character I denotes a beam section trolley insulator embodying my invention. The insulator IU comprises generally a longitudinal beam insulating member II having end fittings I2, such as shown, of well-known construction, secured thereto for engaging adjacent ends of a trolley wire I3 or other well known forms of xtures.

In one form of my invention, in order to secure the necessary tensile strength and insulating qualities, the beam I I may comprise both insulating material and metallic members formed as a unitary member. In this instance, the beam II comprises similar metallic strain members I5 which fimction as a metallic core for the beam and through which the bolts I6 extend to secure the end iittings I2 in position.

As will be readily understood, the metallic members I 5 must not only be securely joined together but must be insulated from one another. They may be jointed together by means of a joint comprising two complementary beveled surfaces having a plurality of interlocking members thereon, such as the flaring tenons I 1. These surfaces are so disposed that the tenons Il of the one strain member I5 are positioned in the grooves I8 of the other strain member. Suitable insulating material I9 is interposed between the interlocking tenons I'.' and grooves I8 to maintain the strain members I5 in fixed relation and insulate them from each other.

'Io aid in binding the strain members I5 together and to protect the insulating material I9 from exposure to the weather, an enveloping insulating shell 2| may be provided about the intei-locked strain members I5 in any suitable manner, such as by winding impregnated paper or cloth about them under pressure from heated rolls. This provides a unitary beam structure having the necessary strength and insulating qualities.

In order to relieve the body member II from wear and the destructive effects of arcing, an insulating sheath 22 may be detachably secured to the lower side of the body member II in any well known manner, such as by insulating bolts 23 passing through the body member II The insulating sheath 22 may be formed in any desirable manner, such as a U-section 'channel having iiaring sides which tend to disperse an arc away from the body member as it rises, thus protecting the body member II from the burning effects of arcing.

It has been observed that a section insulator of a type embodying my invention has shown additional advantages. Where the metallic strain members of the insulating member have comprised a magnetic material, such as iron, improved electrical performance as well as mechanical strength has resulted.

It appears that under normal operating conditions section insulators are exposed to serious arcing as the current collector leaves the line section of the conductor. This arcing is usually most destructive not only to the end fittings of the insulator but to the insulating member also.

With a section insulator embodying my invention, however, it has been observed that such an arc may be drawn and the end fittings may even be severely burned, without any appreciable damage resulting to the insulating member where the strain members are of a magnetic material. It is therefore obvious that the inclusion in the vicinity of the arc of the magnetic material of the reinforcing members has certain desirable effects, tending to draw the arc out, cool it, and reduce its harmful burning effects.

It may be seen, therefore, that my invention provides a single beam section insulator which not only combines high tensile strength, high insulating value and immunity to moisture, but which uses well known fittings, is easy to manufacture, and inexpensive to maintain.

Since certain further changes may be made in the foregoing construction, and different embodiments of the invention may be made without departing from the scope thereof, it is intended that all the matter set forth in the foregoing description or shown in the accompanying drawing shall be considered as illustrative and not in a limiting sense.

I claim as my invention:

1. A single-beam section insulator for overhead trolley systems, comprising, in combination, a main insulating member formed with a pair of similarly shaped relatively thin interlocked metallic reinforcing members therein, the insulating material of said insulating member being formed about and between said reinforcing members to secure them in fixed relation with each other, end means secured to the main member disposed to secure adjacent ends of a trolley wire, and a renewable wearing surface and arcing shield having outwardly Iiaring sides detachably secured about the under side of the insulating member.

2. A beam insulator for overhead trolley systems comprising, in combination, an insulating main body member having a pair of similar reenforcing metallic members oppositely disposed in spaced relation and separated and enveloped by an insulating sheath to provide a unitary body member, end fittings for securing the main body member in operating relation in the overhead system, and a removable arcing shield and wearing surface secured about the runner edge of the main body member.

3. A beam insulator for overhead trolley systems comprising, in combination, an insulating body member having a pair of similar overlapping reenforcing members of magnetic material disposed within said body member in parallel spaced relation, a laminated sheath of fibrous insulating material formed about and between said members to provide a unitary structure, end members secured to the body member adapted to position said body member, and a fixed wearing sheath removably secured about the under side of the body member to provide a renewable wearing surface and an arc shield for said body member.

4. In a single beam insulator for trolley systems, in combination, a main insulating body member including a pair of thin tapered interlocking metal plates overlapping in opposed relation, insulating material between the plates disposed to hold them apart to maintain them in xed relation to each other, a plurality of layers of impregnated fibrous insulating material moulded about said plates, and detachable end means secured to the body member disposed to position said body member in the trolley system.

5, In an insulator of the single beam type, in combination, a body member comprising a pair of interlocking end plates, insulating material disposed between the end plates to hold them apart, and a shell of insulating material disposed about the plates, terminal members secured to each end plate disposed to engage adjacent ends of a trolley wire, and a renewable sheath of in sulation disposed to provide a wearing surface and arc-shield secured to one edge of the body member.

6. An insulator of the single beam type for trolley systems comprising, in combination, a main insulating body member including a pair of tapered interlocking metal reenforcing end plates formed within the body member and separated by the insulating material of the member, end means secured to the body member for positioning said body member in a trolley system, and a renewable under-run and arc-shield having outwardly inclined upstanding edges adapted to enclose an edge of the main body secured about the lower edge thereof.

7. An insulator of the single beam type for trolley systems comprising, in combination, an insulating main body member having a pair of similar tapered metallic reenforcing members disposed therein in insulated interlocking relation to relieve the insulating material of incident strain, end means secured to the ends of the body member adapted to position the insulator in the trolley system, and a renewable wear portion and arc shield having outwardly flaring upstanding sides secured about an edge of the body member.

8. A section insulator for trolley systems, cornprising, in combination, a main insulating member having a reenforcing core of overlapping metal strain plates so disposed within the main member and insulated from each other that the insulation of the insulating member surrounds said strain plates and maintains them in fixed relation with each other, means secured to the ends of the main member disposed to position the body member in a trolley system, and a detachable wearing sheath and arc-shield secured to the under side of the main member.

9. A section insulator for trolley systems comprising, in combination, a longitudinal insulating beam member of at least two overlapping and interlocking metal plates separated by and enveloped by an insulating material disposed to insulate the plates from each other and to maintain them in xed relation, end means secured to the beam member for engaging adjacent ends of `a trolley wire, and a sheath of insulating material detachably secured to the lower edge of the beam to provide a renewable wearing surface and arc-shield.

LON C. SPENCER. 

